title: Effects of different movement directions on electromyography recorded from the shoulder muscles while passing the target positions.
abstract: OBJECTIVE
  We compared electromyography (EMG) recorded from the shoulder joint muscles in the same position for different movement directions.
  
  
  METHODS
  Fifteen healthy subjects participated. They performed shoulder elevation from 0° to 120°, shoulder depression from 120° to 0°, shoulder horizontal adduction from -15° to 105°, and shoulder horizontal abduction from 105° to -15°. The target positions were 90° shoulder elevation in the 0°, 30°, 60°, and 90° planes (0°, 30°, 60°, and 90° positions). EMG signals were recorded from the supraspinatus (SSP) muscle by fine-wire electrodes. EMG signals from the infraspinatus (ISP), anterior deltoid, middle deltoid, and posterior deltoid muscles were recorded using active surface electrodes.
  
  
  RESULTS
  During elevation and horizontal abduction, the SSP showed significantly higher activity than that shown during depression and during horizontal adduction in the 0°, 30°, and 60° positions. During elevation, the ISP showed significantly higher activity than during depression and during horizontal adduction in the 90° position. During horizontal abduction, the ISP showed significantly higher activity than during depression in the 90° position.
  
  
  CONCLUSIONS
  When the movement tasks were performed in different movement directions at the same speed, each muscle showed characteristic activity.
authors.affiliation: Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan; Department of Rehabilitation, Hitsujigaoka Hospital, Sapporo, Japan.
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Sakaki
authors.forename: Fuminari
authors.initials: F
authors.lastname: Kaneko
authors.forename: Kota
authors.initials: K
authors.lastname: Watanabe
authors.forename: Takuma
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Masaki
authors.initials: M
authors.lastname: Katayose
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Aoki
authors.forename: Eriko
authors.initials: E
authors.lastname: Shibata
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yamashita
mesh_terms: D000328:Adult; D004566:Electrodes; D004576:Electromyography; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009038:Motion; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D017006:Rotator Cuff / Q000502:physiology; D012782:Shoulder / Q000502:physiology*; D012785:Shoulder Joint / Q000502:physiology; D055815:Young Adult
keywords: Electromyography; Motion analysis; Movement direction; Rotator cuff; Shoulder joint